Glass laminates can be used as windows and glazing in architectural and vehicle or transportation applications, including automobiles, rolling stock, locomotive and airplanes. Glass laminates can also be used as glass panels in balustrades and stairs, and as decorative panels or coverings for walls, columns, elevator cabs, kitchen appliances and other applications. As used herein, a glazing or a laminated glass structure can be a transparent, semi-transparent, translucent or opaque part of a window, panel, wall, enclosure, sign or other structure. Common types of glazing that are used in architectural and/or vehicular applications include clear and tinted laminated glass structures.
Conventional automotive glazing constructions for side panels typically include a 5 mm thick monolithic soda lime glass layer or two plies of 2.1 mm or 2.0 mm soda lime glass with an intermediate tri-layer acoustic interlayer. These constructions have certain advantages, including low cost and a sufficient impact resistance for automotive and other applications. However, because of their limited impact resistance and higher weight, these laminates exhibit poor performance characteristics, including a higher probability of breakage when struck by roadside debris, vandals and other objects of impact as well as well as lower fuel efficiencies for a respective vehicle.
As noted above such glass window panes are heavy and prone to breakage from rock strike or other forms of vandalism. Efforts have been made to replace the glass window panes with polymer window panes as they are inherently lighter in weight than the glass window panes and can be less prone to breakage. Polymer window panes are also prone to breakage and often cannot meet the Federal Railway Regulations for ballistic and block testing. Furthermore, polymer window panes are prone to scratches and must be replaced at regular intervals. Furthermore, polymer window panes are generally not capable of passing strict flammability tests, for example, one or more of the Federal Aviation Regulations, the European Regulations, and British Regulations.
In applications where strength is important, the strength of conventional glass can be enhanced by several methods, including coatings, thermal tempering, and chemical strengthening (ion exchange). Thermal tempering is conventionally employed in such applications with thick, monolithic glass sheets, and has the advantage of creating a thick compressive layer through the glass surface, typically 20 to 25% of the overall glass thickness. The magnitude of the compressive stress is relatively low, however, typically less than 100 MPa. Furthermore, thermal tempering becomes increasingly ineffective for relatively thin glass, e.g., less than about 2 mm. In contrast, ion exchange (IX) techniques can produce high levels of compressive stress in the treated glass, as high as about 1000 MPa at the surface, and is suitable for very thin glass.
Tempered glass (both thermally tempered and chemically tempered) has the advantage of being more resistant to breakage which can be desirable to enhance the reliability of laminated automobile glazing. In particular, thin, chemically-tempered glass can be desirable for use in making strong, lighter-weight auto glazing. Thus, there is a need to provide an improved automotive laminate structure. Furthermore, there is a need to provide an improved window system comprising a polymer, for example, that is capable of passing one or more of the Federal Aviation Regulations, the European Regulations, the British Regulations, and the Federal Railway Regulations.